ASSESSMENT OF CONTAMINATION BY ALUMINIUM AND HEAVY METALS IN SEDIMENTS AND WATER OF A FRENCH PORT USING ALUMINIUM SACRIFICIAL ANODES

摘要

Ports infrastructures are generally protected by cathodic protection using aluminium sacrificial anodes. Anodes are then dissolved in seawater and Al can accumulate in sediments. This study was led in the framework of the European EFFORTS project. Investigations were realized on sediments and water from a French port, which uses aluminium sacrificial anodes. The aim was to estimate the possible contamination level and the chemical speciation of aluminium. Moreover, a special interest was given to heavy metals. Different sites were sampled in 2007. Surface water and interstitial water samples were analysed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) for the determination of Al, Cd, Cr, Co, Cu, Ni, Pb, Si, and Zn. Total metal concentrations in the sediment were determined after alkaline fusion. A contamination factor was calculated. A cold-acid extraction (HCl 1 mol.L~(-1)) solution and a sequential extraction were conducted in order to evaluate the labile fraction of metals. This study shows relatively weak aluminium level in the port compared to the reference point. The situation is similar for the heavy metals studied except for the site near factories. The Al labile fraction represents 5% or less of the total aluminium, except for the site near factories, for which more than 10% of Al is mobilized.